This invention is directed to a molding composition comprising a blend of a poly(aryl ether), a polyester and a compatibilizing amount of an aromatic polycarbonate. The composition can additionally contain one or more of the following: fiber reinforcement, inorganic particulate filler, impact modifier, or a flame retardant additive.
Filled polyester compositions, particularly fiberglass filled poly(butylene terephthalate) are widely used to mold electrical parts, such as connectors, since such parts have excellent chemical resistance and a high heat distortion temperature. However, the parts molded from a fiberglass filled poly(butylene terephthalate) composition have a tendency to warp to a high degree due to the uneven shrinkage resulting from crystallization of the poly(butylene terephthalate) during molding.
A molded article produced from a composition containing a poly(aryl ether), particularly polysulfone, fiberglass, and poly(butylene terephthalate) exhibit lower warpage than an article molded from a fiberglass filled poly(butylene terephthalate) composition. However, in several applications, an article molded from a composition of polysulfone, fiberglass, and poly(butylene terephthalate) tended to be brittle. Also, the polysulfone, fiberglass and poly(butylene terephthalate) are relatively incompatible and thus difficult to process into uniform articles.
A molded article produced from a composition containing a poly(aryl ether), particularly, polysulfone, and a polyester, particularly poly(ethylene terephthalate) or poly(butylene terephthalate), without fiberglass has improved chemical and environmental stress crack resistance. However, the components of this composition are also relatively incompatible and thus difficult to process into useful molded articles.
Thus, since compositions containing poly(aryl ether) and polyester have improved properties, a need exists to compatibilize them so that they can easily be processed into molded articles.